Cluster Analysis

The term cluster analysis
(first used by Tryon, 1939) actually encompasses a number of different
classification algorithms which can be used to develop taxonomies (typically
as part of exploratory data
analysis). For example, biologists have to organize the different
species of animals before a meaningful description of the differences
between animals is possible. According to the modern system employed in
biology, man belongs to the primates, the mammals, the amniotes, the vertebrates,
and the animals. Note how in this classification, the higher the level
of aggregation the less similar are the members in the respective class.
Man has more in common with all other primates (e.g., apes) than it does
with the more "distant" members of the mammals (e.g., dogs),
etc. For information on specific types of cluster
analysis methods, see Joining
(Tree Clustering), Two-way
Joining (Block Clustering), and K-means
Clustering.